Casting
in plaster is fun and easy, if you know how to do it right. Most problems
people have casting plaster is in how you begin the mixing of the
plaster and water.
What
I do:
Fill
the mold with water that is going to be cast in plaster.
Empty
the water from the mold into a container you will mix the plaster
in. This will
ensure that your mold will be filled completely with your plaster
mix once the correct amount of water and plaster is mixed.
If you
are going to make more than one casting in the same mold, you can
mark the
container for the water level you added so you don't have to put water
in the mold again.
Next,
prepare the mold with mold release. I use a half and half mixture
of fragrance free dish soap and water and wipe the surface of the
mold and let it dry. Then lightly polish it out and make sure there
isn't any residue left in puddles in the mold.
Once
the mold is ready, start by sprinkling plaster into the water you
have ready in your mixing container until it starts to peak above
the water level. I use my hand to sprinkle the plaster through my
fingers during this stage to make sure there aren't any lumps in the
plaster as it is put in the water.
NOTICE:
THIS IS THE IMPORTANT PART, ADD THE PLASTER
INTO THE WATER, DO NOT ADD WATER TO PLASTER. THIS IS THE SECRET TO
MAKING THE PERFECT CASTING!
Let the
plaster set in the water for a minute or two, and then with a rubber
spatula, or disposable stick, mix the plaster and water for a couple
minutes and try not to raise and lower the mixer utensil so you don't
introduce any air bubbles into the mix.
Pour
the mixture slowly into the mold until it is up to the level you want
the casting to be
and tap the table to get any trapped air bubbles to release from the
surface of the mold.
At this
point, you will want to add a wire or string to the back of the casting
for hanging if you are going to do that. It is easy to do if you have
a small stick spanning the mold sides to support the wire until the
plaster sets.
Any extra
plaster can be poured into a small mold you might have setting around
and prepared with mold release or poured into a disposable container
of some type.
DO
NOT RINSE MIXING CONTAINERS DOWN A SINK OR DRAIN, EVEN A THIN MIX
WILL
SETTLE OUT AND SET UP CAUSING PROBLEMS!
I wait
at least a couple hours before taking the casting out of the molds.
They might be set up enough in 20 minutes or so, but they are still
going to be very soft and easy to break.
Place
the castings where they can get plenty of air flow to dry well. After
they are dry,
you can paint them, stain them, carve them, and finish them in many
ways.
Cast
plaster can be cut, drilled, sanded, and bonded to other surfaces
using construction adhesive, sheetrock mud, and some glues.
I hope
this information has been helpful; if you have any questions at all,
please feel free to email us for more
information.
